shuttle threads

The threads in the OVERSEWING method
which pass through each loop created by the
needles of th machine. Punches descend from above
penetrate the paper, and then with draw. The
needles then enter from below and, when they reach
the top o the pile of leaves making up the
"section," they drop slightly leaving a series of
loops of thread through which the shuttle needles
carry their thread from left and right, meeting in
the center. A they reach the center, two catch
teeth emerge and snag the threads, holding them
until the shuttles retract. Th, cycle is then
completed and the head of the machine drops,
tightening th loops around the shuttle threads. It
is therefore, the shuttle threads which secure the
individual oversewing stitches in the "section."